GENETIC VARIABILITY ANALYSIS IN F3 POPULATION DERIVED THROUGH INTRASPECIFIC HYBRIDIZATION IN OILSEED BRASSICA
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Date
2023
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Abstract
Brassica juncea is an allotetraploid with the genomes AA and BB from Brassica rapa and Brassica nigra, respectively. It belongs to the Brassicaceae/Cruciferae family. It is world’s third most important source of edible oil after soybean and oil palm.
Indian mustard has the genetic potential for higher yield and is the predominant oilseed Brassica in India. But due to its longer crop duration, the harvesting time coincides with the pre-monsoon showers resulting in crop loss. Therefore, the development of short-duration high-yielding Indian mustard varieties that can be incorporated into the rice-based cropping sequence of Assam will play a crucial, role in increasing the average yield of rapeseed-mustard in Assam.
The genetic diversity found in the available germplasm of a particular crop is wholly responsible for the success of any breeding strategy. The current study revealed significant variation for all the 17 yield attributing characters. All the characters under study have demonstrated high broad sense heritability. Plant height, number of primary branches, number of secondary branches, number of seeds per siliqua, 1000 seed weight, number of siliqua on main shoot, seed yield per plant, seed yield per hectare, biological yield per plant, harvest index, lesion size, number of lesions on infected leaves number of infected leaves per plant and number of infected plants per plot demonstrated high heritability coupled with high genetic advance.
Correlation coefficients and path coefficients together provide more reliable information that may be used to effectively create crop improvement strategies. Results of the correlation studies demonstrated that seed yield per hectare had a strong positive correlation with days to maturity, biological yield per plant, and seed yield per plant. Path analysis of the current study revealed that the character, and number of infected plants per plot followed by seed yield per plant had the maximum direct effect on seed yield per hectare.
Alternaria blight caused by Alternaria brassicae (Berk) Sacc. is one of the important diseases of rapeseed-mustard affecting the quality and quantity of seed. In the 25 populations that were assessed for disease incidence in field, five genotypes, PM-22, PHR-2 X PM-21, PM-21 X PM-22, PM-21 X Pusa Karishma and PM-27 were shown to have a moderate level of disease resistance.
The Artificial inoculation of test genotypes is necessary to produce a more uniform disease occurrence for precise screening. Out of the 10 genotypes that were assessed for disease incidence through artificial inoculation the genotype PM-22, exhibited moderate resistance.
Molecular markers are effective, precise, and reliable than other types of markers for genetic study of plants in distinguishing closely related species and cultivars. In the current study, 15 SSR markers were evaluated, and 12 of them were shown to be polymorphic.
Therefore, the experimental findings revealed that the analysis of variance components will assist in the selection of the parents to develop better recombinants for use in future breeding projects to develop early maturing mustard genotypes that are appropriate for Assam's agroclimatic condition and have a maximum impact on traits that affect yield. The genotypes that exhibited resistance to Alternaria blight can be used for additional in-depth investigation regarding the host-resistance mechanism to develop resistant mustard varieties to Alternaria blight.